Abstract
INTRODUCTION: To present the global, regional, and national burden of knee osteoarthritis (KOA) and its causative factors, categorized by age, gender, and sociodemographic indices from 1990 to 2021, and to project future trends to 2035. METHODS: A comprehensive analysis of KOA epidemiology was conducted using data from the 2021 Global Burden of Disease Study (GBD). The study examined change trends in KOA burden between 1990 and 2021, including prevalence, incidence, disability-adjusted life years (DALYs), and associated risk factors. Health inequality analyses were performed using slope index of inequality (SII) and concentration index (CI). Decomposition analysis was conducted to understand the contributions of population growth, aging, and epidemiological changes to the increasing burden. Future projections were made for global, Chinese, and Indian trends to 2035. RESULTS: In 2021, the global prevalence of KOA was 374.7 million cases, with an annual incidence of 3.0846 million cases, totaling 12.01 million DALYs. Age-standardized rates for prevalence, incidence, and DALYs increased by 8.3%, 7.1%, and 8.2% respectively since 1990. Health inequality analyses revealed widening disparities across SDI levels, with SII for crude incidence rates increasing from 251 to 400 per 100,000 between 1990 and 2021. Decomposition analysis showed population growth as the primary driver of increased burden globally (75.07% for DALYs), with variations across SDI regions. Projections to 2035 indicate substantial increases in global burden, with incidence expected to rise by 33.6%, prevalence by 43.8%, and DALYs by 41.4%. China and India show differing patterns in projected burden increases. CONCLUSION: KOA remains a significant public health concern with increasing burden and widening health inequalities. The projected increases highlight the need for targeted interventions, especially in rapidly growing populations. Preventive measures should focus on reducing high BMI, implementing gender-specific treatments, and addressing regional disparities to mitigate the future burden of KOA.